The polymerase chain reaction (PCR) is a process that is employed for amplifying nucleic acid molecules. In a typical process, a sample is subjected to a number of thermal cycles, each of which includes a heating stage and a codling stage. By selecting appropriate temperatures during the stages, a sample can be subjected to denaturation, annealing, and elongation conditions until the number of copies of the desired nucleic acid segment (e.g., gene) has increased exponentially. Nowadays, PCR is often employed by way of a device known as a thermocycler.
In WO/2009/105499, there is described an improved thermocycler for PCR. The apparatus described therein addresses performance problems associated with typical art-disclosed thermocyclers. As one means to improving performance, that publication describes generally a system by which at least two thermoelectric modules (each including a thermoelectric device (TED) and an associated heat exchanger) are placed in spatial opposition in which any number of sample vessels are placed in the interior region between the thermoelectric modules.
Notwithstanding the improvements that result in performance from the apparatus of WO/2009/105499, there remains a need in the art for additional efficient thermocycler devices. There also remains a need in the art for improved approaches to the operation of such devices so that reliable and consistent amplification is achieved efficiently, and with relatively low risk of damage to samples, equipment or both, during operation.
Moreover, there continues to be a need to address obstacles that confront many thermocycler devices occasioned by thermal inertia characteristics, namely the heat transfer performance of a mass that is influenced by combination of its thermal conductivity, size, heat capacity, and the dead time inherent to the control operation. There also remains a need for a system that accounts for potential lags in thermal processing due to the execution of one or more electronic control operations and the behavior of the hardware components employed therein.